Figures

Figure 4.28 Precambrian Gaia and evolution of the biosphere. (a) Changes in climate in a live and lifeless world; there is a sharp fall in temperature when oxygen appears. (b) The changing abundance in atmospheric gases. (c) Changes in the
composition of ecosystems: both the photosynthesizers and methanogens increase initially when oxygen appears but the
methanogens eventually decline to a much lower level of abundance. (Population is the proportion of the total population in
tenths.) (From Lovelock 1998.)